(a). Field of the Invention
The present invention relates to a method of preparing an electrode for a lithium based secondary cell, and more particularly, to a method of economically preparing an electrode for a lithium based secondary cell by a simple manufacturing process and for fabricating the lithium based secondary cell having a long lifetime.
(b). Description of the Related Art
Currently, the trend is to miniaturize and lighten portable electronics such as camera systems, audio systems, lap-top personal computers and cellular phones. Therefore, it is required to use cells having a small size, light weight and improved performance characteristics for such electronics.
As lithium satisfy such characteristics, lithium based secondary cells are generally used for that purpose. The lithium based secondary cell utilizes alkali metals such as lithium or carbon for negative active materials while using transition metal compounds for positive active materials. As an electrolyte, liquid or polymer electrolyte is used.
Among the lithium based secondary cells, a lithium ion cell are less chemically reactive and is safer than the other lithium based cells because it dose not contain metallic lithium. Furthermore, the lithium ion cell has relatively high operating voltage and a long cycle life. Owing to the characteristics, the demand of the lithium ion cell has increased in portable consumer electronics.
The lithium ion cell uses lithium-rich or lithium-source intercalation compounds for the positive active material, lithium-accepting or lithium-sink intercalation compounds for the negative active material, and liquid organic or polymer electrolyte. The cell using the liquid organic electrolyte is called a liquid lithium ion cell and the cell using the polymer electrolyte is called a solid-polymer lithium ion cell, a lithium ion polymer cell or a plastic lithium ion cell (PLIB).
An electrode of the lithium ion polymer cell is prepared from a mixture of an active material, a conductive agent, a binder and a plasticizer. The mixture is then applied to a glass substrate and cast into a film type. Thereafter, the resulting active material film is laminated with a current collector. However, the lamination method involves complicated processing steps and requires a higher production cost. Furthermore, an adhesive strength between the active material and the current collector becomes relatively loose.